@article{SF_1980__19_134369,
     author = {H.J. Weinert},
     title = {S-sets and semigroups of quotients.},
     journal = {Semigroup forum},
     pages = {1--78},
     publisher = {mathdoc},
     volume = {19},
     year = {1980},
     zbl = {0404.20051},
     url = {http://geodesic.mathdoc.fr/item/SF_1980__19_134369/}
}